The prototype isolate of HCV was characterized in U.S. Patent Application Serial No. 122,714 (See also EPO Publication Nos. 318,216; 388,232). As used herein, the term “HCV” includes new groups, genotypes and isolates of the same viral species. The term “HCV-1” is used in the same sense as in EPO Publication No. 318,216.
HCV is a transmissible disease distinguishable from other forms of viral-associated liver diseases, including that caused by the known hepatitis viruses, i.e., hepatitis A virus (HAV), hepatitis B virus (HBV), and delta hepatitis virus (HDV), as well as the hepatitis induced by cytomegalovirus (CMV) or Epstein-Barr virus (EBV). HCV was first identified in blood-transfused individuals. Post-transfusion hepatitis (PTH) occurs in approximately 10% of transfused patients, and HCV accounts for up to 90% of these cases. The disease frequently progresses to chronic liver damage (25–55%).
There presently exists a great need to control the translation process with respect to viral nucleic acids. Control of the translation process may constitute an effective therapy for viral disease. By way of example, without limitation, the ability to decrease the expression of viral proteins may limit the disease. The ability to increase the expression of viral proteins in vivo may give rise to strong immune stimulation. The ability to increase the expression of viral proteins may also produce greater amounts of viral proteins which can be more readily purified.
The HCV genome is comprised of a single positive strand of RNA. A schematic representation of the HCV genome is depicted in FIG. 1. The HCV genome possesses a continuous, translational open reading frame (ORF) that encodes a polyprotein of about 3,000 amino acids. In the ORF, the structural protein(s) appear to be encoded in approximately the first quarter of the N-terminal region, with the remainder of the polyprotein responsible for encoding non-structural proteins.
The HCV genome has an area at the 5′ end which is not known to translate any proteins or polypeptides. The region is referred to as the 5′ untranslated region (5′UT region or 5′ UTR) or the 5′ leader region.
The 5′UT region contains up to five upstream ORFs, the first four of which are overlapping in HCV-1, the prototype HCV isolate (Choo et al., “Genetic organization and diversity of the hepatitis C virus,” Proc. Natl. Acad. Sci. USA (1991) 88:2451–2455; Han et al., “Characterization of terminal regions of hepatitis C viral RNA: Identification of conserved sequences in the 5′ untranslated region and poly(A) tails at the 3′ end,” Proc. Natl. Acad. Sci. (USA) (1991) 88:1711–1715). The 5′UT region is homologous in nucleotide sequence to pestiviruses (Han et al.).
Primer extension analysis has revealed that two prominent species of HCV RNA exist in samples derived from infected patients (Han et al.). One of the species is longer, and is presumed to be full-length genomic RNA. The longer, full-length genomic RNA has a 5′ terminus which is predicted to form a hairpin structure (Han et al.; Inchauspe et al., Abstract, Third International Symposium on HCV, V. 19, Strasbourg, France, 1991; Okamoto et al., “Nucleotide sequence of the genomic RNA of hepatitis C virus isolated from a human carrier: Comparison with reported isolates for conserved and divergent regions,” J. Gen Virol. (1991) 72:2697–2704). The remaining species is shorter, presumably a 5′ subgenomic RNA, the 5′ terminus of which starts 145 nucleotides from the 5′ terminus of the longer RNA (Han et al.).
Antisense polynucleotide molecules for HCV are generally disclosed in EP Publication No. 388,232.